Trinucleus

noun

Tri·​nucleus

"+

: a widely distributed genus (the type of the family Trinucleidae) of Ordovician trilobites in which the glabella and cheeks form three rounded elevations on the head

Word History

Etymology

New Latin, from tri- + nucleus

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!